The build-up of amyloid proteins in living tissue, a condition known as amyloidosis, is either the cause or a major factor in the pathology of many so-called amyloid diseases such as Alzheimer's Parkinson's, Huntington's, and prion diseases. Historically, aggregations of protein were classified as amyloid if they displayed apple-green birefringence under polarized light when stained with the dyes Congo red or Thioflavin T (ThT) (Sipe and Cohen, 2000, J. Struct. Biol. 130:88-98). That definition of amyloid has been expanded in recent years to apply to any polypeptide which can polymerize in a cross-beta sheet conformation in vitro or in vivo, regardless of sequence (Xu, 2007, Amyloid 14:119-31). Certain types of amyloidosis may occur principally in the central nervous system, as with aggregation of beta-amyloid protein in Alzheimer's Disease, tau protein in progressive supranuclear palsy, alpha-synuclein in Parkinson's Disease, huntingtin protein in Huntington's Disease, and prion protein in Creutzfeldt-Jacob and other prion diseases. Other types of amyloidosis are systemic in nature, as with aggregation of transthyretin in senile systemic amyloidosis.
All of the above listed diseases are invariably fatal using current medical practice. In none of these diseases is there any known, widely accepted therapy or treatment that can halt and/or reverse the aggregation of amyloid deposits. As such there remains an urgent need for treatments.